Corrections

It's frequently beneficial to add post hoc corrections to mean-field calculations to compensate for certain inaccuracies in the theory. Rowan supports use of Grimme's empirical "D3" dispersion correction, which has been shown to dramatically improve the performance of Hartree–Fock and density-functional theory calculations (e.g.).

Available dispersion corrections depend on the calculation engine and method. For supported methods, Rowan supports D3 with Becke–Johnson damping (d3bj) and D4 (d4). Composite methods can also include corrections as part of their definition.

Request a supported correction through the corrections list, using rowan.Correction.D3BJ or rowan.Correction.D4.

Authenticate by setting ROWAN_API_KEY as described in the Python API guide.

import rowan

# load molecule from smiles
molecule = rowan.Molecule.from_smiles("C1CCCC1")  # cyclopentane

# submit the calculation and wait for its result
workflow = rowan.submit_basic_calculation_workflow(
    initial_molecule=molecule,
    name="opt cyclopentane",
    method=rowan.Method.B3LYP,
    basis_set="vDZP",
    corrections=[rowan.Correction.D3BJ],
    tasks=["optimize", "frequencies"],
)

result = workflow.result()

For instructions on how to select corrections when submitting calculations using the web interface, see the web interface documentation.